Various cleanups to nist.cc.

More flexible testing.
Read and parse the certified cost value from the data file.
Remove the ugly hack for computing the certified cost.
Refactored the flags parsing logic

Change-Id: I8f2e6be183b758b2453302fcdc6696bfa0db5eb8

include/ceres/types.h

@@ -37,6 +37,8 @@
 #ifndef CERES_PUBLIC_TYPES_H_
 #define CERES_PUBLIC_TYPES_H_
 
+#include "ceres/internal/port.h"
+
 namespace ceres {
 
 // Basic integer types. These typedefs are in the Ceres namespace to avoid
@@ -297,16 +299,31 @@ enum DimensionType {
 };
 
 const char* LinearSolverTypeToString(LinearSolverType type);
+bool StringToLinearSolverType(string value, LinearSolverType* type);
+
 const char* PreconditionerTypeToString(PreconditionerType type);
+bool StringToPreconditionerType(string value, PreconditionerType* type);
+
 const char* SparseLinearAlgebraLibraryTypeToString(
     SparseLinearAlgebraLibraryType type);
+bool StringToSparseLinearAlgebraLibraryType(
+    string value,
+    SparseLinearAlgebraLibraryType* type);
+
+const char* OrderingTypeToString(OrderingType type);
+bool StringToOrderingType(string value, OrderingType* type);
+
+const char* TrustRegionStrategyTypeToString(TrustRegionStrategyType type);
+bool StringToTrustRegionStrategyType(string value,
+                                     TrustRegionStrategyType* type);
+
+const char* DoglegTypeToString(DoglegType type);
+bool StringToDoglegType(string value, DoglegType* type);
+
 const char* LinearSolverTerminationTypeToString(
     LinearSolverTerminationType type);
-const char* OrderingTypeToString(OrderingType type);
+
 const char* SolverTerminationTypeToString(SolverTerminationType type);
-const char* SparseLinearAlgebraLibraryTypeToString(
-    SparseLinearAlgebraLibraryType type);
-const char* TrustRegionStrategyTypeToString( TrustRegionStrategyType type);
 bool IsSchurType(LinearSolverType type);
 
 }  // namespace ceres